I need to know what size belt to by pass ac compressor.

well,good luck with that.if you want to know what length belt you need,then when you measure around all the pulleys except the A/C compressor pulley with a tailors tape then you will know!some vehicles,you can remove the compressor and replace it with an A/C bypass pulley and use the same belt,but i don't see one for your truck.i've seen people make 6 or 8 trips to the parts store trying to guess at the length before they get the correct length belt to bypass the A/C pulley! right now you should have an 86.5(865K6) inch belt on it.go to the parts store and get an (810K6) belt.that should be the one,81 inch belt!